A motion picture generally has a soundtrack, and a soundtrack often includes special effects that provide the sensation to an audience that a sound is emanating from a location in a theatre. Such special effects are called herein xe2x80x9cspatial audio effectsxe2x80x9d and include one-dimensional effects (stereo effects, often called xe2x80x9cpanningxe2x80x9d), two-dimensional effects and three-dimensional effects (often called xe2x80x9cspatialization,xe2x80x9d or xe2x80x9csurround soundxe2x80x9d). Such effects may affect the amplitude, for example, of the sound in each speaker.
To create such spatial audio effects, the soundtrack is edited using a stereo or surround sound editing system or a digital audio workstation that has a graphical and/or mechanical user interface that allows an audio editor to specify parameters of the effect. For example, in the Avid Symphony editing system, a graphical xe2x80x9csliderxe2x80x9d is used to define the relative balance between left and right channels of stereo audio. For surround sound, an interface may be used to permit an editor to specify a point in three-dimensional space, from which the relative balance among four or five channels can be determined. Some systems allow the user simultaneously to hear the spatial audio effect and to see a representation of the effect parameters. Using such systems, the settings for various spatial audio effects are set subjectively by the audio editor based on the audio editor""s understanding of how the point of emanation of the sound is related to images in the motion picture.
Displaying visual information from a motion picture in a visual field within a designated extent of a related aural field supports editing of a spatial audio effect for the motion picture. The extent of a related aural field also is displayed. Information specifying a point of origin of a sound used in the spatial audio effect with respect to the visual field is received for each of a number of frames of a portion of the motion picture. This information may be received from a pointing device that indicates a point in the displayed extent of the aural field, or from a tracker that indicates a position of an object in the displayed visual information, or from a three-dimensional model of an object that indicates a position of an object in the displayed visual field. Using the specified point of origin and the relationship of the visual and aural fields, parameters of the spatial audio effect may be determined, from which a soundtrack may be generated. Information describing the specified point of origin may be stored. The frames for which points of origin are specified may be key frames that specify parameters of a function defining how the point of origin changes from frame to frame in the portion of the motion picture. The relationship between a visual field and an aural field may be different for each of the plurality of frames in the motion picture. This relationship may be specified by displaying the visual information from the motion picture and an indication of the extent of the aural field to a user, who in turn, through an input device, may indicate changes to the extent of the aural field with respect to the visual information.